This invention relates to dental devices and procedures used in the formation of custom fitted dental prosthesis and especially to a dental alignment instrument for a dentist or a dental lab technician to acquire the proper bite angle of a patient.
Dental prostheses, such as crowns, bridges, veneers, dentures and related dental procedures are well known in the art for restoring damaged or missing teeth within the mouth of a patient. In general terms, the area to be restored is initially prepared by the dentist, such as by reducing a damaged tooth by drilling and shaping procedures, to form a suitable base adapted to receive and support a prosthetic crown. The prepared area including adjacent and opposing tooth and gum structures is then replicated by means of a dental impression defined typically by a curable vinyl elastomer or the like carried on a suitably shaped impression tray which is placed into the patient's mouth for the duration of a short cure cycle. The dental impression is then used to form the appropriate mold or molds from which the desired dental prosthesis is formed, normally from a castable gold alloy or the like. Other types of dental prostheses may require an imprint of the patient's bite registration.
The dental impression or bite imprint is commonly fitted into a dental articulator in the course of producing the requisite mold or molds for the final prosthesis. However, in accordance with standard dental laboratory procedures, the dental articulator is oriented horizontally to correspondingly reproduce a horizontal patient bite line or angle. Unfortunately, the actual bite angle in many patients deviates from a horizontal plane. As a result, the prosthesis is shaped for precision custom fit according to a horizontal patient bite line which does not in fact exist. When the dentist attempts to place the prosthesis into the patient's mouth, an improper or unsatisfactory fit is recognized. Since most bite angle deviations are relative small, the dentist normally tries to remedy the prosthesis misfit by trial and error grinding of the prosthesis. This approach can be extremely costly to the dentist by substantially increasing the time needed for proper prosthesis fit and placement. Moreover, and more importantly, trial and error attempts to reshape the prosthesis often result in a poor fit and resultant poor service life and patient dissatisfaction.
In the past, dental appliances have been proposed particularly in the field of orthodontics for use in measuring the patient's bite line or angle. However, such appliances have been relatively costly and difficult to use, and further have not provided a bite angle indication which can be satisfactorily communicated to and reproduced at a dental laboratory located typically at a different facility. Accordingly, in spite of the aforementioned problems attributable to bite angle variations, the general dental practice has been to ignore the problem or otherwise accommodate bite angle deviations by estimation and/or trial and error procedures.
Prior U.S. Patents relating to dental instruments can be seen in the Frisbie U.S. Pat. No. 5,069,619 for a dental impression tray with a level indicator which is provided with a level indicator to indicate a patient's bite angle. The impression tray is placed into the mouth of the patient and holds the level indicator to indicate the patient's bite angle, particularly with respect to deviations from a horizontal plane. The bite angle information is used subsequently in dental laboratory procedures to accommodate the specific bite angle in the formation of a dental prosthesis. In the Lee et al. U.S. Pat. No. 6,109,917, a system for establishing a reference plane for dental casts is provided so that the patient's teeth can be oriented to a horizontal reference plane. The apparatus includes a face bow with an adjustable nasion relator assembly and a level gauge and a bite fork.
In the Diamond U.S. Pat. Nos. 4,474,555 and 4,422,849 and 4,455,137, a dental instrument and method for positioning an orthodontic bracket is disclosed and has a housing on which is positioned an arm that includes a means for releasably holding the orthodontic bracket and includes level indicating means used for displaying the extend of inclination of the arm with respect to a predetermined plane. The Hernandez U.S. Pat. No. 3,693,260 is a multi-purpose adjustable occlusal fork. A horizontal bite plate support is combined with a dental articulator which has a calibrated vertical post member which has a connection to support a face bow in a position to establish the location of a patient's transverse mandible hinge axis. The Jaccard Patent No. 4,908,949 is an air bubble level for portable tools. The Keller Patent No. 5,738,517 is an apparatus and method of fixed reference examination of dental patients and includes a bubble level carried by a face bow. The Andrews Patent No. 5,176,515 is a dental treatment method and apparatus which includes a level.
The present invention is a dental device and procedure used in the formation of custom fitted lab fabricated dental prosthesis, such as crowns, fixed bridges, removable dentures, and interior veneers. The dental instrument is used to improve dental bite registration accordingly to the patient's horizontal and vertical angles by the dentist and transferred to the lab technician to permit the formation of a prosthesis. A lab technician can continuously check the horizontal and vertical line angles while fabricating the dental appliance.